Data storage and retrieval systems are used to store information provided by one or more host computer systems. Such data storage and retrieval systems receive requests to write information to one or more secondary storage devices, and requests to retrieve information from those one or more secondary storage devices. Upon receipt of a write request, the system stores information received from a host computer in a data cache. In certain implementations, a copy of that information is also stored in a nonvolatile storage device. Upon receipt of a read request, the system recalls one or more tracks from the one or more secondary storage devices and moves those tracks to the data cache.
Thus, the system is continuously moving information to and from storage devices, and to and from the data cache. One or more device adapters interconnect the data cache and the information storage devices. What is needed is an apparatus and method to manage the tracks residing in the data cache such that tracks having a low reuse potential are preferentially demoted from the cache while tracks having a high reuse potential are preferentially kept in the cache.